The asthmatic athlete: metabolic and ventilatory responses to exercise with and without pre-exercise medication

To determine whether asthmatic athletes have normal physiological responses to exercise without pre-exercise medication, we studied 17 female and male asthmatic subjects, 9 highly trained (HT) and 8 moderately trained (MT) under 2 conditions: salbutamol (S) 200 micrograms taken via inhaler 15 minutes prior to exercise or placebo (PL). The exercise task was 4 continuous 5 minute increments representing 25, 50, 75 and 90% of the subject's VO2max.VO2, minute ventilation (VE), respiratory exchange ratio (RER), % saturation (SaO2), and HR were continuously measured during exercise. Blood lactate (LA) was measured each minute throughout exercise and recovery. Post-medication, exercise, and recovery measurements of peak expiratory flow rates (PEFR) were made using a Mini-Wright flow meter. No differences (p > 0.05) between treatment conditions were found at any stage of exercise with respect to VO2, VE, RER, HR and SaO2. However, among the HT group the mean HR for the 4 exercise conditions was significantly higher under PL (PL = 151.7;S = 147.2; p = 0.01). No difference was found in LA during exercise or in recovery. Pre-exercise PEFR was significantly higher when pretreatment was S(S = 582; PL = 545 l.sec-1; p = 0.003). During the exercise and recovery conditions mean PEFR measures were significantly higher (S = 600.1; PL = 569.6; p = 0.002) with the S treatment. Bonferroni's test detected a difference in PEFR measures between S and PL at 25% and 50% VO2max and 3 and 15 minutes into recovery. There was no difference in the physiological response to exercise between groups based on training status. It was concluded that although S affects the PEFR these asthmatic athletes do not have altered metabolic or ventilatory responses during this incremental exercise protocol.